Aircraft with tilting fan assemblies

ABSTRACT

Embodiments provide an aircraft with one or more tilting fan assemblies that are configured to tilt between a forward flight position and a vertical lift position. The aircraft may also include a plurality of lift fan assemblies for vertical movement. The tilting fan assemblies may be coupled to the fuselage or wings of the aircraft via one or more tilting mechanisms. A control system coupled to the aircraft may control the one or more tilting mechanisms to move the tilting fan assemblies between the forward flight position and the vertical lift position. The tilting fan assemblies may be coupled to one or more support structures that are coupled the fuselage or wings of the aircraft.

RELATED APPLICATIONS

This application claims benefit under 35 USC § 119(e) to U.S.Provisional Patent Application No. 62/968,852 filed Jan. 31, 2020 andentitled “Aircraft with Tilting Fans”, the disclosure of which isincorporated by reference herein in their entirety for all purposes.

FIELD

The described embodiments relate generally to an aircraft with verticaltakeoff and landing capability. In particular, the embodiments providean aircraft with one or more tilting fan assemblies which providevertical and horizontal thrust in a controlled fashion for hover,transition and cruise flight.

BACKGROUND

Aircrafts with vertical takeoff and landing capability need lift fans tobe able to hover, takeoff and land vertically. However, such aircraftsalso need forward thrust to be able to cruise in the air. Thrustproduced in the vertical direction provides lift to the vehicle; thrustproduced horizontally provides forward movement. A vertical takeoff andlanding (VTOL) aircraft should produce both vertical and horizontalthrust, and be able to control these forces in a balanced fashion.

SUMMARY

Various embodiments provide an aircraft configured for vertical takeoffand landing. The aircraft comprises a fuselage, a pair of wings coupledto opposite sides of the fuselage, a plurality of lift fan assembliescoupled to the pair of wings, a plurality of tilting fan assemblies anda control system. The plurality of lift fan assemblies are configured tocreate a vertical lift. The plurality of tilting fan assemblies areconfigured to move between a vertical lift position and a forward flightposition. The control system is configurable to control the plurality oftilting fan assemblies between the vertical lift position and theforward flight position.

Some embodiments provide an aircraft configured for vertical takeoff andlanding. The aircraft comprises a fuselage, a pair of wings coupled toopposite sides of the fuselage, a plurality of tilting fan assembliescoupled to the pair of wings configured to move between a vertical liftposition and a forward flight position, and a control systemconfigurable to control the plurality of tilting fan assemblies betweenthe vertical lift position and the forward flight position. Theplurality of tilting fan assemblies are configured to create a verticallift when in the vertical lift position. The aircraft further includesone or more battery units including a plurality of battery cellsconfigured to power the plurality of tilting fan assemblies.

Embodiments provide a method performed by a control system coupled to anaircraft configured for vertical takeoff and landing for controlling oneor more tilting fan assemblies of the aircraft. The control systemreceives a flight instruction, determines a position of a plurality oftilting fan assemblies coupled to the aircraft, controls one or more ofthe plurality of tilting fan assemblies between a vertical lift positionand a forward flight position based on the flight instruction; andcontinuously monitors the position of the plurality of tilting fanassemblies in view of the flight instruction.

If the flight instruction is a takeoff instruction or a landinginstruction, the control system controls the one or more of theplurality of tilting fan assemblies that are in the forward flightposition to the vertical lift position. If the flight instruction is aforward flight instruction, the control system controls the one or moreof the plurality of tilting fan assemblies that are in the vertical liftposition to the forward flight position.

These and other embodiments are described in further detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A depicts a simplified schematic of an exemplary VTOL aircraft,according to various embodiments.

FIG. 1B illustrates top, planar, side and front views (clockwisestarting from the top left corner) of the VTOL aircraft with a pair oftilting fan assemblies in the forward flight position, according tovarious embodiments.

FIG. 1C illustrates top, planar, side and front views (clockwisestarting from the top left corner) of the VTOL aircraft with a pair oftilting fan assemblies in the vertical lift position, according tovarious embodiments.

FIG. 2B illustrates top, planar, side and front views (clockwisestarting from the top left corner) of the VTOL aircraft with fronttilting fan assemblies in the vertical lift position, according tovarious embodiments.

FIG. 3A illustrates top, planar, side and front views (clockwisestarting from the top left corner) of the VTOL aircraft with tilting fanassemblies in the forward flight position, according to variousembodiments.

FIG. 3B illustrates top, planar, side and front views (clockwisestarting from the top left corner) of the VTOL aircraft with tilting fanassemblies in the vertical lift position, according to variousembodiments.

FIG. 4 is a flow chart illustrating an embodiment of a process tocontrol flight of a VTOL aircraft through a transition between verticaland forward flight, according to various embodiments.

DETAILED DESCRIPTION

Techniques disclosed herein relate generally to an aircraft with aplurality of lift fan assemblies, and at least one tilting fan assembly.More specifically, techniques disclosed herein provide a VTOL aircraftwith a plurality of lift fan assemblies for vertical movement, and oneor more tilting fan assemblies that are configured to tilt between aforward flight position and a vertical lift position for forwardmovement. Various inventive embodiments are described herein, includingmethods, processes, systems, devices, and the like.

In order to better appreciate the features and aspects of the fanassembly orientations for aircrafts according to the present disclosure,further context for the disclosure is provided in the following sectionby discussing particular implementations of a VTOL aircraft according toembodiments of the present disclosure. These embodiments are for exampleonly and other fan configurations can be employed in connection with theVTOL aircraft described herein.

FIG. 1A depicts a simplified schematic of an exemplary VTOL aircraft100. According to various embodiments, the VTOL aircraft 100 may be anelectrically powered aircraft. In some embodiments, the VTOL aircraft100 may be configured to carry one or more passengers and/or cargo, andmay be controlled automatically and/or remotely (e.g. may not require anon-board pilot to operate the aircraft, and may be controlled based on acontrol signal or instruction received from a remote entity). In theexample shown in FIG. 1A, the VTOL aircraft 100 includes a fuselage 102which may include a cabin section 140 for carrying passengers and/orcargo. For example, the cabin section 140 may be provided toward a noseof the VTOL aircraft 100. The VTOL aircraft 100 may also include ahorizontal stabilizer (e.g. a tailplane) 130 coupled to a rear end ofthe fuselage 102. The tailplane 130 may be in any suitable shape orform. For example, the tailplane 130 may be V-shaped (e.g. V-tail). Apair of wings (e.g. a first wing 106 and a second wing 108) are coupledto opposite sides of the fuselage 102. In some embodiments, the pair ofwings may be coupled to the fuselage in a high-wing configuration. Thatis, the pair of wings may be mounted on an upper portion of thefuselage, as shown in FIG. 1A. A plurality of fan assemblies (e.g. liftfan assemblies and/or tilting fan assemblies) may be coupled to the pairof wings. For example, the VTOL aircraft 100 may include a total of 12fan assemblies (e.g. fans, rotors, propellers) divided equally betweenthe wings. In some embodiments, the fan assemblies may be coupleddirectly to the wings. In other embodiments, the fan assemblies may bemounted on support structures 104, such as booms that may be coupled toan underside of the wings 106, 108.

According to some embodiments, each wing 106, 108 may include twosupport structures (e.g. booms) 104 each including a pair of lift fanassemblies (also known as “lift fans”) 110 mounted thereon. For example,each lift fan assembly maybe coupled to an end of the boom 104 such thata first lift fan assembly 113 is in front of the wing 106, 108 and asecond lift fan assembly 110 is aft of the wing 106, 108. In someembodiments, the two lift fan assemblies 110, 113 coupled to oppositeends of the boom 104 may have their blades mounted with opposite anglesof attack and thus, the two lift fan assemblies 110, 113 may spin inopposite directions. The lift fan assemblies 110, 113 are configured tocreate a vertical lift for the VTOL aircraft 100.

According to various embodiments, each lift fan assembly 110 may be inform of an electric motor-driven rotor (e.g. a combined fan and motor),and may be configured to move the aircraft 100 in the vertical directionduring, for example, take-off, hovering and/or landing. The rotor maycomprise blades attached to a hub, or may be manufactured as a singlepiece with an integral hub. The hub provides a central structure towhich the blades connect, and in some embodiments is made in a shapethat envelops the motor. In some embodiments the motor parts arelow-profile so that the entire motor fits within the hub of the rotor,presenting lower resistance to the air flow when flying forward. Therotor is attached to the rotating part of the motor. The stationary partof the motor is attached to the boom 104. In some embodiments the motoris a permanent magnet motor and is controlled by an electronic motorcontroller. The electronic motor controller sends electrical currents tothe motor in a precise sequence to allow the rotor to turn at a desiredspeed or with a desired torque.

The lift fan assembly 110 may have any suitable number of blades thatmay be oriented in a predetermined manner. The orientation of the liftfan assemblies may be fixed (e.g. the lift fan assemblies 110 may bemounted in a fixed position relative to the wings 106, 108). In someembodiments, one or more of the lift fan assemblies 110 may beconfigured to be repositioned relative to the wings 106, 108 manually orin response to a control signal (e.g. from a control system 150, such asa flight control system, controlling the VTOL aircraft 100). Accordingto various embodiments, the lift fan assembly 110 may have 2 bladeshaving a predetermined angle of attack. In some embodiments, twoadjacent lift fan assemblies (e.g. lift fan assembly 110 and lift fanassembly 111) may have opposite angle of attacks such that the twoadjacent fan assemblies spin in opposite directions. The two adjacentlift fan assemblies may be on a same wing (e.g. lift fan assemblies 110and 111 in FIG. 1A) or on opposite wing (e.g. lift fan assemblies 117and 119 in FIG. 1B). According to various embodiments, a first subset ofthe lift fan assemblies may spin in a first direction, and a secondsubset (e.g. remainder) of the lift fan assemblies may spin in a seconddirection, opposite to the first direction.

In some embodiments, each wing 106, 108 may include at least one supportstructure (e.g. boom) 112 carrying at least one tilting fan assembly 114(also known in various embodiments as “propeller assembly” or “propellerfan assembly”). The tilting fan assembly 114 is configured to movebetween a forward flight position (as illustrated in FIG. 1B) and avertical lift position (as illustrated in FIG. 1C). The boom 112 withthe at least one tilting fan assembly 114 may be in addition to orinstead of the boom(s) carrying lift fan assemblies. The tilting fanassembly 114 may be switched (e.g. rotated) between a forward flightposition (illustrated in FIGS. 1A-1B) and a vertical lift position(illustrated in FIG. 1C). The tilting fan assembly 114 may be coupled tothe boom 112 via a tilting mechanism 116 including, for example, motorsand coupling mechanisms. In the forward flight position, the tilting fanassembly 114 may be substantially in a vertical orientation with respectto the fuselage 102. In the vertical lift position, the tilting fanassembly 114 may be substantially in a horizontal orientation withrespect to the fuselage 102.

Each tilting fan assembly 114 may include a combined rotor and motor.The rotor may comprise blades attached to a hub, or may be manufacturedas a single piece with an integral hub. The hub provides a centralstructure to which the blades connect, and in some embodiments is madein a shape that envelops the motor. In some embodiments the motor partsare low-profile so that the entire motor fits within the hub of therotor, presenting lower resistance to the air flow when flying forward.The rotor is attached to the rotating part of the motor. The stationarypart of the motor is attached to the boom 112 or other part of thefuselage 102. In some embodiments the motor is a permanent magnet motorand is controlled by an electronic motor controller. The electronicmotor controller sends electrical currents to the motor in a precisesequence to allow the rotor to turn at a desired speed or with a desiredtorque. The tilting fan assembly 114 may have any suitable number ofblades that may be oriented in a predetermined manner. For example, thetilting fan assembly 114 may have 5 blades having a predetermined angleof attack.

According to various embodiments, the tilting fan assembly 114 on thefirst wing 108 may tilt simultaneously with the tilting fan assembly 124on the second wing 106. For example, the control system 150 of theaircraft may control at least a subset of the plurality of tilting fanassemblies simultaneously. That is, the control system 150 may operatethe respective tilting mechanisms 116 and 126 substantially at a sametime. In some embodiments, the tilting mechanisms 116 and 126 may beoperated independently from each other. According to some embodiments,the control system 150 may be configurable to control the VTOL aircraft100 (e.g. control the position of the tilting fan assemblies)automatically and/or remotely (e.g. via a control signal received from aremote entity, such as a remote controller, a remote pilot or a remotecontrol tower). In various embodiments, the control system 150 comprisesone or more processors configured to perform the processing and controlfunctions described herein.

In some embodiments, each wing 106, 108 may also include at least onesupport structure (e.g. boom) 112 carrying one lift fan assembly 110(e.g. an aft fan assembly) and one tilting fan assembly 114. For examplethe lift fan assembly 110 may be coupled aft of the wing 106, 108 andthe tilting fan assembly 114 may be coupled forward of the wing 106,108. According to various embodiments, a plurality of lift fanassemblies may be coupled to a tailing edge of the pair or wings 106,108 and/or a plurality of tilting fan assemblies may be coupled to aleading edge of the pair of wings 106, 108 via one or more tiltingmechanism(s).

The exemplary VTOL aircraft 100 illustrated in FIGS. 1A-1C may include atotal of twelve fan assemblies: ten lift fan assemblies and two tiltingfan assemblies. In some embodiments, at least one (or preferably a pair)of the fan assemblies of the exemplary VTOL aircraft are tilting fanassemblies. The tilting fan assemblies 114 and 124, when in the forwardflight position, may provide the thrust for (and/or transition to)forward flight, climb, descent, and cruise. The lift fan assemblies 110provide enough thrust to lift the aircraft off the ground and maintaincontrol, for example during takeoff, hovering and/or landing. Accordingto various embodiments, the lift fan assemblies 110 may stop operatingduring the forward flight of the VTOL aircraft 100.

One or more battery units 135 may be coupled to the VTOL aircraft 100 topower the fan assemblies (the lift fan assemblies and the tilting fanassemblies). More specifically, the fan assemblies may be driven byelectric motors that are powered by a power system including the one ormore battery units 135. In some embodiments, each fan assembly may havea dedicated battery unit 135. The battery units 135 may be provided onbooms carrying the fan assemblies, within the fuselage or a combinationthereof. Each battery unit 135 may include a plurality of battery cellsconfigured to power the fan assemblies. Accordingly, the VTOL aircraft100 may be an electric aircraft. In alternative embodiments, the VTOLaircraft 100 may be a hybrid-electric aircraft.

FIG. 1B illustrates top, planar, side and front views (clockwisestarting from the top left corner) of the VTOL aircraft 100 with a pairof tilting fan assemblies 114, 124 in the forward flight position.

FIG. 1C illustrates top, planar, side and front views (clockwisestarting from the top left corner) of the VTOL aircraft 100 with a pairof tilting fan assemblies 114, 124 in the vertical lift position.

The control system 150 (e.g. the flight control system) coupled to theaircraft 100 may be configured to control the plurality of tilting fanassemblies between the vertical lift position and the forward flightposition. For example, the control system 150 may be configurable tocontrol the tilting mechanism(s) 116, 126 to switch the positioning ofthe tilting fan assemblies 114, 124 from the forward flight position(illustrated in FIGS. 1A-1B) to the vertical lift position (illustratedin FIG. 1C); as well as from the vertical lift position (illustrated inFIG. 1C) to the forward flight position (illustrated in FIGS. 1A-1B). Insome embodiments, the control system 150 may receive flight data fromone or more sensors (e.g. sensor measuring air temperature, electricmotor temperature, airspeed of the aircraft, etc.), computers, and otherinput/output devices coupled to the aircraft. The control system 150 maythen control the tilting fan assemblies 114, 124 between the twopositions based on sensor data and/or flight data received from thesensors (e.g. sensor measuring air temperature, electric motortemperature, airspeed of the aircraft, etc.), computers, and otherinput/output devices coupled to the aircraft.

According to various embodiments, the control system 150 may beconfigurable to receive a flight instruction, such as a takeoff, hover,cruise or landing instruction. The control system 150 may then determinea position of the plurality of tilting fan assemblies, and control oneor more of the plurality of tilting fan assemblies between the verticallift position and the forward flight position based on the flightinstruction. During the operation of the VTOL aircraft 100, the controlsystem 150 may be configurable to continuously monitor the position ofthe plurality of tilting fan assemblies in view of the flightinstruction.

The exemplary VTOL aircraft 100 illustrated in FIGS. 1A-1C includes apair of tilting fan assemblies 114, 124 one provided on each wing 106,108, closer to the fuselage 102. One of ordinary skill the art willappreciate that the number and location of the tilting fan assemblies isnot limited to that illustrated in FIGS. 1A-1C and that the VTOLaircraft can include less or more number of tilting fan assembliesand/or lift fan assemblies. For example, according to an embodiment, theboom 112 may switch places with any one of the booms 104. According toyet another embodiment, all front fan assemblies (or all aft fanassemblies) may be tilting fan assemblies.

FIGS. 2A-2B illustrate another exemplary embodiment of the VTOL aircraftwith tilting fan assemblies. In the exemplary embodiment illustrated inFIGS. 2A-2B, a plurality of lift fan assemblies are provided at atailing edge of the pair of wings and a plurality of tilting fanassemblies are provided at a leading edge of the pair of wings. Theexemplary VTOL aircraft 200 illustrated in FIGS. 2A-2B includes allfront fan assemblies configured as tilting fan assemblies 204. Thus, inthe exemplary VTOL aircraft 200, all booms 206 are identical and eachincludes a tilting fan assembly 204 on one end and a lift fan assembly202 on the opposite end. Since all booms 206 are identical, the booms206 may be interchangeable between the positions on the wings. Forexample, the first boom closer to the fuselage may be interchangeablewith the adjacent second boom (e.g. the middle boom on the wing) or thethird boom further away from the fuselage. In some embodiments, eachtilting fan assembly 204 may be coupled to the boom 206 via anindividual tilting mechanism 208. For example, at least three tiltingfan assemblies may be coupled to each of the pair of wings, as shown inFIG. 2A.

FIG. 2A illustrates top, planar, side and front views (clockwisestarting from the top left corner) of the VTOL aircraft 200 with fronttilting fan assemblies 204 in the forward flight position.

FIG. 2B illustrates top, planar, side and front views (clockwisestarting from the top left corner) of the VTOL aircraft 200 with fronttilting fan assemblies 204 in the vertical lift position (e.g. fronttilting fan assemblies 204 facing upward toward the sky).

The control system 250 (e.g. a flight control system) coupled to theaircraft 200 may be configured to control the tilting mechanisms 208 toswitch the positioning of the tilting fan assemblies 204 from theforward flight position (illustrated in FIG. 2A) to the vertical liftposition (illustrated in FIG. 2B); as well as from the vertical liftposition (illustrated in FIG. 2B) to the forward flight position(illustrated in FIG. 2A). According to various embodiments, the controlsystem 250 may control the tilting fan assemblies 204 between the twopositions based on sensor data and/or flight data received from thesensors (e.g. sensor measuring air temperature, electric motortemperature, airspeed of the aircraft, etc.), computers, and otherinput/output devices coupled to the aircraft.

The tilting fan assemblies 204 may be coupled to the wings via one ormore tilting mechanisms, and the tilting fan assemblies 204 may becontrolled individually via the tilting mechanisms 208. The flightcontrol system may be configured to control the tilting mechanisms 208simultaneously so as to position all tilting fan assemblies 204 in asame position at the same time. Alternatively, the flight control systemmay be configured to control the tilting mechanisms 208 independentlyfrom each other. This way, the flight control system may identify one ormore tilting fan assemblies 204 and control the identified tilting fanassemblies 204 independently from the rest of the tilting fanassemblies. According to various embodiments, the flight control systemmay use symmetric and/or asymmetric tilting to augment control duringhovering and transition (e.g. transition between vertical lift andforward flight). The additional degree of freedom of tilting may augmentcontrol during motor out and nominal conditions.

While FIGS. 2A-2B illustrate the tilting fan assemblies 204 on the front(e.g. leading) edge of the wings and the lift fan assemblies 202 on theaft (e.g. tailing) edge of the wings, this configuration is forillustrative purposes and should not be construed as limiting. In someembodiments, the lift fan assemblies 202 may be provided on the leadingedge of the wings and the tilting fan assemblies 204 on the tailing edgeof the wings.

Yet in other embodiments, the tilting fan assemblies 204 and the liftfan assemblies 202 may be alternated on each one of the front and rearportions of the wings. For example, the leading edge of the first wingmay include a first tilting fan assembly 204, a lift fan assembly 202and a second tilting fan assembly 204. The leading edge of the secondwing may include a tilting fan assembly 204, a lift fan assembly 202 andanother tilting fan assembly 204. Alternatively, the leading edge of thesecond wing may include a first lift fan assembly 202, a tilting fanassembly 204, and a second lift fan assembly 202. Similar configurationsmay be applied to the tailing edge of the first and second wings aswell.

While FIGS. 1A-2B illustrate the plurality of tilting fan mechanismscoupled to the wings, in alternative embodiments the plurality oftilting fan mechanisms may be coupled to the fuselage. For example, theplurality of tilting fan mechanisms may be coupled to one or morelateral support structures (e.g. lateral booms) that are coupled to thefuselage.

FIGS. 3A-3B illustrate another embodiment of the VTOL aircraft withtilting fan assemblies. The VTOL aircraft 300 illustrated in FIGS. 3A-3Bincludes a lateral boom 310 provided in front of the wings, closer to anose of the aircraft. One or more tilting fan assemblies 314, 324 arecoupled to the lateral boom 310. In some embodiments, the lateral boom310 may be a tilting boom tilting around an axis parallel to a lateralaxis of the aircraft, thereby moving the tilting fan assemblies 314, 324at the same time between a forward flight position (illustrated in FIG.3A) and a vertical lift position (illustrated in FIG. 3B). In suchembodiments, it may not be necessary to couple the tilting fanassemblies 314, 324 to the lateral boom 310 via tilting mechanisms ifthe lateral boom itself is a tilting boom. The tilting of the lateralboom 310 may be controlled to modify the position of the tilting fanassemblies 314, 324. In other embodiments, both the lateral boom and thetilting fan assemblies may tilt independently from each other (e.g. thetilting fan assemblies 314 may be coupled to the tilting lateral boomvia one or more tilting mechanisms).

The lateral boom 310 may be formed as a single boom or may be formed astwo separate lateral booms coupled to opposite sides of the fuselage.The lateral boom(s) 310 may be coupled to the fuselage forward of thepair of wings.

Similar to the embodiment illustrated in FIGS. 1A-1C, the exemplary VTOLaircraft 300 illustrated in FIGS. 3A-3B includes two booms 304 eachcarrying a pair of lift fan assemblies 302 on each wing. The exemplaryVTOL aircraft 300 further includes a shorter boom 306 coupled to eachwing, extending only on one side of each wing (e.g. aft side) carrying asingle lift fan assembly 308. As illustrated in FIGS. 3A-3B, theexemplary VTOL aircraft includes 10 lift fan assemblies and 2 tiltingfan assemblies.

FIG. 3A illustrates top, planar, side and front views (clockwisestarting from the top left corner) of the VTOL aircraft 300 with tiltingfan assemblies 314, 324 in the forward flight position.

FIG. 3B illustrates top, planar, side and front views (clockwisestarting from the top left corner) of the VTOL aircraft 300 with tiltingfan assemblies 314, 324 in the vertical lift position.

The control system 350 (e.g. the flight control system) coupled to theaircraft 300 may be configured to control the tilting fan assemblies314, 324 from the forward flight position (illustrated in FIG. 3A) tothe vertical lift position (illustrated in FIG. 3B); as well as from thevertical lift position (illustrated in FIG. 3B) to the forward flightposition (illustrated in FIG. 3A). According to various embodiments, thecontrol system may control the tilting of the tilting fan assemblies314, 324 between the two positions based on sensor data and/or flightdata received from the sensors (e.g. sensor measuring air temperature,electric motor temperature, airspeed of the aircraft, etc.), computers,and other input/output devices coupled to the aircraft.

In embodiments where the lateral boom 310 is a tilting boom, the controlsystem 350 may be configured to control the tilting of the lateral boom310 to switch the positioning of the tilting fan assemblies 314, 324from the forward flight position (illustrated in FIG. 3A) to thevertical lift position (illustrated in FIG. 3B); as well as from thevertical lift position (illustrated in FIG. 3B) to the forward flightposition (illustrated in FIG. 3A). According to various embodiments, thecontrol system may control the tilting of the lateral boom 310 betweenthe two positions based on sensor data and/or flight data received fromthe sensors (e.g. sensor measuring air temperature, electric motortemperature, airspeed of the aircraft, etc.), computers, and otherinput/output devices coupled to the aircraft.

In some embodiments, the lateral boom 310 may be provided behind thewings, closer to a tail of the aircraft (or on the tail of theaircraft). In such embodiments, the shorter boom 306 that extends onlyon one side of each wing carrying a single lift fan assembly 308 mayextend toward the leading edge of the wing(s).

According to an alternative embodiment, the tilting fan assemblies 314,324 may be coupled to the lateral boom 310 via respective tiltingmechanisms. Thus, the lateral boom 310 itself may or may not be atilting boom. In such embodiments, the tilting fan assemblies 314, 324may be controlled to switch position (between the vertical lift positionand forward flight position) individually. In such embodiments, it maystill be possible to do an emergency landing by eliminating a failed(e.g. broken or stuck) tilting fan assembly, and controlling theremaining tilting fan assemblies from a forward flight position to avertical lift position. For example, the tilting fan assemblies 314, 324may be individually controlled to switch position at the same time. Yetaccording to another example, the tilting fan assemblies 314, 324 may beindividually controlled to switch position at different times (e.g.consecutively, one after another).

According to various embodiments, any number of lift fan assemblies maybe coupled to the VTOL aircraft. For example, the aircraft may include 3lift fan assemblies coupled to each wing (as shown in FIG. 2A), or theaircraft may include 5 lift fan assemblies coupled to each wing (asshown in FIGS. 1A and 3A). Other embodiments may include no lift fanassemblies (e.g. the lift is created using the tilting fan assemblies inthe vertical position, therefore the aircraft may include any number oftilting fan assemblies), 2 lift fan assemblies, 4 lift fan assemblies,or 6 (or more) lift fan assemblies. According to various embodiments,the combined number of lift fan assemblies and the tilting fanassemblies coupled to the aircraft may be at least 12.

In various embodiments, a control system such as the flight controlsystem of the aircraft may be configured to control the actuators(rotors, aerodynamic control surfaces, the tilting fan assemblies, thelift fan assemblies) of the aircraft to cause the aircraft to transitionbetween a vertical lift (e.g. liftoff/hovering/landing) mode and aforward flight mode. For example, the control system may be configuredto receive a flight instruction, such as a liftoff instruction, ahovering instruction, a landing instruction or a forward flightinstruction. If the flight instruction is a takeoff instruction or alanding instruction, the control system may control the one or more ofthe plurality of tilting fan assemblies that are in the forward flightposition to the vertical lift position. If the flight instruction is aforward flight instruction, the control system may control the one ormore of the plurality of tilting fan assemblies that are in the verticallift position to the forward flight position. The control system maythen determine a position of a plurality of tilting fan assembliescoupled to the aircraft and control one or more of the plurality oftilting fan assemblies between a vertical lift position and a forwardflight position based on the flight instruction. The control system maycontinuously monitor the position of the plurality of tilting fanassemblies in view of the flight instruction.

FIG. 4 is a flow chart illustrating an embodiment of a process tocontrol flight of a VTOL aircraft configured for vertical takeoff andlanding through a transition between vertical lift and forward flight.

At step S400, the aircraft may be in a stationary position on theground. For example, the aircraft may be parked at a charging stationfor charging the batteries. Alternatively, the aircraft may be parked ata location awaiting to receive cargo or passengers. The flight controlsystem of the VTOL aircraft may receive a flight plan (e.g. from theautopilot, a pilot or a remote controller pilot) to arrive at apredetermined destination. The flight plan may include an instruction totakeoff from the ground.

At step S402, the flight control system may determine whether alltilting fan assemblies of the aircraft are in a vertical lift position.According to various embodiments, it may be desirable to have all fanassemblies in the vertical lift position to create a vertical lift. Insome embodiments, the aircraft may be configured to keep all tilting fanassemblies in a vertical lift position when the aircraft is not in use(e.g. is parked on the ground or is being charged).

If it is determined, at step S402, that not all fan assemblies are in avertical lift position, the flight control system may control one ormore of the tilting fan assemblies that are in a forward flight positionto switch to a vertical lift position (step S404). For example, one ormore of the tilting fan assemblies may have been switched to the forwardflight position while the aircraft was on the ground for testing ormaintenance purposes.

At step S406, the flight control system may initiate a takeoff sequenceto lift the aircraft off of the ground. During the takeoff sequence, thelift fan mechanisms and the tilting fan mechanisms in a vertical liftposition may all be activated.

At step S408, after a certain amount of time has passed since performingstep S406, the flight control system may receive an instruction totransition to forward flight. Before switching to the forward flightmode, the control system may check one or more of the altitude, speedand orientation of the aircraft to ensure that the parameters are withina predetermined, desirable range. In some embodiments, the controlsystem may communicate the parameters to a remote entity (e.g. a remotecontrol tower. a remote pilot).

In various embodiments, transition to forward flight may be effected byattaining a desired altitude (e.g., design minimum or greater than athreshold) and rotating the tilting fan assemblies substantiallycontinuously to a forward flight position, while adjusting power to therotors as required to maintain stability and altitude while increasingforward airspeed as the tilting fan assemblies are rotated into theforward flight position and begin to generate sufficient lift tomaintain altitude.

Upon receiving the instruction to transition to forward flight, at stepS410, the control system may control one or more of the tilting fanassemblies to switch from a vertical lift position to a forward flightposition. In some embodiments, the tilting fan assemblies may becontrolled substantially simultaneously.

At step S412, the control system may receive an instruction (e.g. fromthe autopilot, a pilot or a remote entity) to hover or to land. Inresponse, at step S414, the flight control system may control one ormore of the tilting fan assemblies to switch from the forward flightposition to the vertical lift position. At step S416, the flight controlsystem may initiate a hovering or landing sequence to hover or land theaircraft on the ground.

The various embodiments discussed herein are illustrated in FIGS. 1A-3Busing an aircraft with a specific tail. However, the embodiments are notlimited to the specific tail or aircraft configuration illustrated inthe figures. One or ordinary skill in the art will appreciate that theembodiments can be combined with aircraft with alternative tails or withalternative designs, including but not limited to an aircraft with aconventional tail, an aircraft with multiple tails, or an aircraft withno tail.

For simplicity, various active and passive circuitry components are notshown in the figures. In the foregoing specification, embodiments of thedisclosure have been described with reference to numerous specificdetails that can vary from implementation to implementation. Thespecification and drawings are, accordingly, to be regarded in anillustrative rather than a restrictive sense. The sole and exclusiveindicator of the scope of the disclosure, and what is intended by theapplicants to be the scope of the disclosure, is the literal andequivalent scope of the set of claims that issue from this application,in the specific form in which such claims issue, including anysubsequent correction. The specific details of particular embodimentscan be combined in any suitable manner without departing from the spiritand scope of embodiments of the disclosure.

Electronic components of the described embodiments may be speciallyconstructed for the required purposes, or may comprise one or moregeneral-purpose computers selectively activated or reconfigured by acomputer program stored in the computer. Such a computer program may bestored in a computer readable storage medium, such as, but is notlimited to, any type of disk including floppy disks, optical disks,DVDs, CD-ROMs, magnetic-optical disks, read-only memories (ROMs), randomaccess memories (RAMs), EPROMs, EEPROMs, magnetic or optical cards,application specific integrated circuits (ASICs), or any type of mediasuitable for storing electronic instructions, and each coupled to acomputer system bus.

Additionally, spatially relative terms, such as “front or “back” and thelike can be used to describe an element and/or feature's relationship toanother element(s) and/or feature(s) as, for example, illustrated in thefigures. It will be understood that the spatially relative terms areintended to encompass different orientations of the device in use and/oroperation in addition to the orientation depicted in the figures. Forexample, if the device in the figures is turned over, elements describedas a “front” surface can then be oriented “back” from other elements orfeatures. The device can be otherwise oriented (e.g., rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein interpreted accordingly.

What is claimed is:
 1. An aircraft configured for vertical takeoff andlanding, the aircraft comprising: a fuselage; a pair of wings coupled toopposite sides of the fuselage; a plurality of lift fan assembliescoupled to the pair of wings, wherein the plurality of lift fanassemblies are configured to create a vertical lift; a plurality oftilting fan assemblies configured to move between a vertical liftposition and a forward flight position; and a control systemconfigurable to control the plurality of tilting fan assemblies betweenthe vertical lift position and the forward flight position.
 2. Theaircraft of claim 1, further comprising: one or more battery unitsincluding a plurality of battery cells configured to power the pluralityof tilting fan assemblies and the plurality of lift fan assemblies. 3.The aircraft of claim 1 further comprising: a tailplane in form of aV-tail coupled to a rear end of the fuselage.
 4. The aircraft of claim1, wherein the pair of wings are coupled to the fuselage in a high-wingconfiguration.
 5. The aircraft of claim 1, wherein the plurality of liftfan assemblies are mounted in a fixed position relative to the pair ofwings to move the aircraft in a vertical direction.
 6. The aircraft ofclaim 5, wherein one or more of the plurality of lift fan assemblies areconfigurable to stop operating during a forward flight of the aircraft.7. The aircraft of claim 5, wherein each of the plurality of lift fanassemblies comprise an electric motor-driven rotor.
 8. The aircraft ofclaim 5, wherein at least three lift fan assemblies are coupled to eachof the pair of wings.
 9. The aircraft of claim 1, wherein the pluralityof tilting fan assemblies are coupled to at least one of the pair ofwings via one or more tilting mechanisms.
 10. The aircraft of claim 9,wherein at least three tilting fan assemblies are coupled to each of thepair of wings.
 11. The aircraft of claim 1, wherein a combined number oflift fan assemblies and tilting fan assemblies is at least
 12. 12. Theaircraft of claim 1, further comprising: a plurality of supportstructures coupled to an underside of the pair of wings, wherein a liftfan assembly among the plurality of lift fan assemblies is coupled to afirst end of each support structure.
 13. The aircraft of claim 12,wherein at least one of the plurality of tilting fan assemblies iscoupled to a second end of a first support structure among the pluralityof support structures via a tilting mechanism.
 14. The aircraft of claim12, wherein a tilting fan assembly among the plurality of tilting fanassemblies is coupled to a second end of each support structure.
 15. Theaircraft of claim 12, wherein a second lift fan assembly is coupled to asecond end of at least one support structure among the plurality ofsupport structures.
 16. The aircraft of claim 1, further comprising: oneor more lateral support structures coupled to the fuselage, wherein theplurality of tilting fan assemblies are coupled to the one or morelateral support structures.
 17. The aircraft of claim 16, wherein theone or more lateral support structures are tilting around an axisparallel to a lateral axis of the aircraft.
 18. The aircraft of claim16, wherein the one or more lateral support structures are coupled tothe fuselage forward of the pair of wings.
 19. The aircraft of claim 1,wherein the plurality of lift fan assemblies are provided at a tailingedge of the pair of wings and the plurality of tilting fan assembliesare provided at a leading edge of the pair of wings.
 20. The aircraft ofclaim 1, wherein the control system is configurable to: receive a flightinstruction; determine a position of the plurality of tilting fanassemblies; control one or more of the plurality of tilting fanassemblies between the vertical lift position and the forward flightposition based on the flight instruction; and continuously monitor theposition of the plurality of tilting fan assemblies in view of theflight instruction.
 21. The aircraft of claim 20, wherein the controlsystem is configurable to: control the position of the tilting fanassemblies based on flight data received by sensors coupled to theaircraft.
 22. The aircraft of claim 20, wherein the control system isconfigurable to: control the position of the tilting fan assembliesautomatically.
 23. The aircraft of claim 20, wherein the control systemis configurable to: control the position of the tilting fan assembliesbased on a signal received from a remote entity.
 24. The aircraft ofclaim 20, wherein the control system is configurable to: control a firsttilting fan assembly and a second tilting fan assembly among theplurality of tilting fan assemblies independently from each other. 25.The aircraft of claim 20, wherein the control system is configurable tocontrol: at least a subset of the plurality of tilting fan assembliessimultaneously.
 26. An aircraft comprising: a fuselage; a pair of wingscoupled to opposite sides of the fuselage; a plurality of tilting fanassemblies coupled to the pair of wings, wherein the plurality oftilting fan assemblies are configured to move between a vertical liftposition and a forward flight position, wherein the plurality of tiltingfan assemblies are configured to create a vertical lift when in thevertical lift position; one or more battery units including a pluralityof battery cells configured to power the plurality of tilting fanassemblies; and a control system configured to control the plurality oftilting fan assemblies between the vertical lift position and theforward flight position.
 27. The aircraft of claim 26, furthercomprising: a plurality of support structures coupled to an underside ofthe pair of wings, wherein at least one of the plurality of tilting fanassemblies is coupled to an end of a first support structure among theplurality of support structures via a tilting mechanism.
 28. Theaircraft of claim 26, further comprising: a plurality of supportstructures coupled to an underside of the pair of wings, wherein atilting fan assembly among the plurality of tilting fan assemblies iscoupled to an end of each support structure.
 29. The aircraft of claim26, wherein the plurality of tilting fan assemblies are coupled to aleading edge of the pair of wings via one or more tilting mechanisms.30. The aircraft of claim 26, wherein at least three tilting fanassemblies are coupled to each of the pair of wings.
 31. The aircraft ofclaim 26, wherein the control system is configurable to control a firsttilting fan assembly and a second tilting fan assembly among theplurality of tilting fan assemblies independently from each other. 32.The aircraft of claim 26, wherein the control system is configurable tocontrol at least a subset of the plurality of tilting fan assembliessimultaneously.
 33. The aircraft of claim 26, wherein the control systemis configurable to control a position of the tilting fan assembliesbased on flight data received by sensors coupled to the aircraft. 34.The aircraft of claim 26, wherein the control system is configurable tocontrol a position of the tilting fan assemblies automatically.
 35. Theaircraft of claim 26, wherein the control system is configurable tocontrol a position of the tilting fan assemblies based on a signalreceived from a remote entity.
 36. The aircraft of claim 26, furthercomprising: a tailplane in form of a V-tail coupled to a rear end of thefuselage.
 37. A method for controlling one or more tilting fanassemblies of an aircraft, the method comprising: receiving, by acontrol system coupled to an aircraft, a flight instruction;determining, by the control system, a position of a plurality of tiltingfan assemblies coupled to the aircraft, wherein the aircraft isconfigured for vertical takeoff and landing; controlling, by the controlsystem, one or more of the plurality of tilting fan assemblies between avertical lift position and a forward flight position based on the flightinstruction; and continuously monitoring, by the control system, theposition of the plurality of tilting fan assemblies in view of theflight instruction.
 38. The method of claim 37, further comprising:controlling, by the control system, a first tilting fan assembly and asecond tilting fan assembly among the plurality of tilting fanassemblies independently from each other.
 39. The method of claim 37,further comprising: controlling, by the control system, at least asubset of the plurality of tilting fan assemblies simultaneously. 40.The method of claim 37, further comprising: controlling, by the controlsystem, the position of the plurality of tilting fan assembliesautomatically.
 41. The method of claim 37, further comprising:controlling, by the control system, the position of the plurality oftilting fan assemblies based on a signal received from a remote entity.42. The method of claim 37, wherein the flight instruction is a takeoffinstruction, and wherein controlling the one or more of the plurality oftilting fan assemblies comprises: determining whether each of theplurality of tilting fan assemblies is in the vertical lift position;and controlling the one or more of the plurality of tilting fanassemblies to the vertical lift position.
 43. The method of claim 37,wherein the flight instruction is a hover instruction or a landinginstruction, and wherein controlling the one or more of the plurality oftilting fan assemblies comprises: controlling the one or more of theplurality of tilting fan assemblies to the vertical lift position. 44.The method of claim 37, wherein the flight instruction is an instructionto switch to forward flight, and wherein controlling the one or more ofthe plurality of tilting fan assemblies comprises: controlling the oneor more of the plurality of tilting fan assemblies to the forward flightposition.
 45. The method of claim 44, further comprising: controllingone or more of a plurality of lift fan assemblies to stop operatingduring the forward flight of the aircraft.
 46. The method of claim 37,further comprising: receiving, by the control system, flight data fromone or more sensors coupled to the aircraft; and controlling theposition of the plurality of tilting fan assemblies based on the flightdata received from the one or more sensors coupled to the aircraft.